Re: [libvirt] [PATCH v1 05/31] virpcimock: Create driver_override file in device dirs

Newer kernels (v3.16-rc1~29^2~6^4) have 'driver_override' file which simplifies way of binding a PCI device to desired driver. Libvirt has support for this for some time too (v2.3.0-rc1~236), but not our virpcimock. So far we did not care because our code is designed to deal with this situation. Except for one. hypothetical case: binding a device to the vfio-pci driver can be successful only via driver_override. Any attempt to bind a PCI device to vfio-pci driver using old method (new_id + unbind + bind) will fail because of b803b29c1a5. While on vanilla kernel

I'm able to use the old method successfully, it's failing on RHEL kernels (not sure why).

Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- tests/virpcimock.c | 57 +++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 51 insertions(+), 6 deletions(-) diff --git a/tests/virpcimock.c b/tests/virpcimock.c index 6865f992dc..18d06d11d4 100644 --- a/tests/virpcimock.c +++ b/tests/virpcimock.c @@ -87,6 +87,11 @@ char *fakesysfspcidir; * Probe for a driver that handles the specified device. * Data in format "DDDD:BB:DD.F" (Domain:Bus:Device.Function). * + * /sys/bus/pci/devices/<device>/driver_override + * Name of a driver that overrides preferred driver can be written + * here. The device will be attached to it on drivers_probe event. + * Writing an empty string (or "\n") clears the override. + * * As a little hack, we are not mocking write to these files, but close() * instead. The advantage is we don't need any self growing array to hold the * partial writes and construct them back. We can let all the writes finish, @@ -147,6 +152,7 @@ static struct pciDevice *pci_device_find_by_content(const char *path); static void pci_driver_new(const char *name, int fail, ...); static struct pciDriver *pci_driver_find_by_dev(struct pciDevice *dev); static struct pciDriver *pci_driver_find_by_path(const char *path); +static struct pciDriver *pci_driver_find_by_driver_override(struct pciDevice *dev); static int pci_driver_bind(struct pciDriver *driver, struct pciDevice *dev); static int pci_driver_unbind(struct pciDriver *driver, struct pciDevice *dev); static int pci_driver_handle_change(int fd, const char *path); @@ -202,7 +208,8 @@ make_symlink(const char *path, static int pci_read_file(const char *path, char *buf, - size_t buf_size) + size_t buf_size, + bool truncate) { int ret = -1; int fd = -1; @@ -224,7 +231,8 @@ pci_read_file(const char *path, goto cleanup; } - if (ftruncate(fd, 0) < 0) + if (truncate && + ftruncate(fd, 0) < 0) goto cleanup; ret = 0; @@ -398,6 +406,8 @@ pci_device_new_from_stub(const struct pciDevice *data) ABORT("@tmp overflow"); make_file(devpath, "class", tmp, -1); + make_file(devpath, "driver_override", NULL, -1); + if (snprintf(tmp, sizeof(tmp), "%s/../../../kernel/iommu_groups/%d", devpath, dev->iommuGroup) < 0) { @@ -441,7 +451,7 @@ pci_device_find_by_content(const char *path) { char tmp[32]; - if (pci_read_file(path, tmp, sizeof(tmp)) < 0) + if (pci_read_file(path, tmp, sizeof(tmp), true) < 0) return NULL; return pci_device_find_by_id(tmp); @@ -450,7 +460,10 @@ pci_device_find_by_content(const char *path) static int pci_device_autobind(struct pciDevice *dev) { - struct pciDriver *driver = pci_driver_find_by_dev(dev); + struct pciDriver *driver = pci_driver_find_by_driver_override(dev); + + if (!driver) + driver = pci_driver_find_by_dev(dev); if (!driver) { /* No driver found. Nothing to do */ @@ -544,6 +557,36 @@ pci_driver_find_by_path(const char *path) return NULL; } +static struct pciDriver * +pci_driver_find_by_driver_override(struct pciDevice *dev) +{ + struct pciDriver *ret = NULL; + char *path = NULL; + char tmp[32]; + size_t i; + + if (virAsprintfQuiet(&path, + SYSFS_PCI_PREFIX "devices/%s/driver_override", + dev->id) < 0) + return NULL; + + if (pci_read_file(path, tmp, sizeof(tmp), false) < 0) + goto cleanup; + + for (i = 0; i < nPCIDrivers; i++) { + struct pciDriver *driver = pciDrivers[i]; + + if (STREQ(tmp, driver->name)) { + ret = driver; + break; + } + } + + cleanup: + VIR_FREE(path);

+ return ret; +} + static int pci_driver_bind(struct pciDriver *driver, struct pciDevice *dev) @@ -657,6 +700,8 @@ pci_driver_handle_change(int fd ATTRIBUTE_UNUSED, const char *path) ret = pci_driver_handle_remove_id(path); else if (STREQ(file, "drivers_probe")) ret = pci_driver_handle_drivers_probe(path); + else if (STREQ(file, "driver_override")) + ret = 0; /* nada */ else ABORT("Not handled write to: %s", path); return ret; @@ -711,7 +756,7 @@ pci_driver_handle_new_id(const char *path) goto cleanup; } - if (pci_read_file(path, buf, sizeof(buf)) < 0) + if (pci_read_file(path, buf, sizeof(buf), true) < 0) goto cleanup; if (sscanf(buf, "%x %x", &vendor, &device) < 2) { @@ -766,7 +811,7 @@ pci_driver_handle_remove_id(const char *path) goto cleanup; } - if (pci_read_file(path, buf, sizeof(buf)) < 0) + if (pci_read_file(path, buf, sizeof(buf), true) < 0) goto cleanup; if (sscanf(buf, "%x %x", &vendor, &device) < 2) { -- 2.21.0 -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list